Liquefied gas dispensing system



`Patented Sept. 14, 1948 "UNITED STATES PATENT ,oFFlcE LIQUEFIED vGASDISPENSING SYSTEM Loyd J. White,` San Antonio, Tex., assignor toSouthern Steel Company, San Antonio, Tex., a corporationof TexasApplication October 2, 1944, Serial No. 556,832

vaporized; thence, through a vaporizer to com-v plete the vaporizationof the residual liquid; and,

l thence. through a second-stage pressure reducer to a service pipe, asgenerally illustrated in my U. S. Patents Nos. 2,176,829 and 2,260,356,and in my copending application Ser. No, 237,113, filed October 28,1938. The main object of the present invention is to provide a new typeof vaporizer which is removably associated with the storage tank andutilizes heat derived from the fuel contents of' the tank and, from asupplemental, exi ternal heating medium, not only to insure completevaporization of the residual liquid, but also to augment the supply ofheat delivered to the liquid fuel in the tank. Another aim is to pro#vide a new type of re-vaporizer or heat exchanger for liquid fuelcondensate formed in the service line and associated with the vaporizer,also to absorb heat from the fuel contents of the tank and from thesupplemental heating medium, the arrangement being such that both thevaporizing and re-vaporizing units are incorporated in a compositeassembly.

Other aims and advantages of the invention will appear in thespecification, when considered in connection with the accompanyingdrawing, in which:

Fig. l .is a vertical sectional view of an'underground system embodyingthe invention, parts being shown in elevation;

Fig. 2 is a sectional view taken on the line 2-2 of Fig. 1; and

Fig. 3 is a longitudinal sectional view of the heat exchanger shown inFig. 1.

Referring particularly to the drawing, and to the type of undergroundliquefied dispensing system shown therein, it will be understood thatthis invention applies to two-stage liquid eduction systems of thegeneral type disclosed in the aforesaid Patents Nos. 2,176,829 and2,260,356, wherein commercial butane, which usually contains from to 25%propane, is discharged, in the liquid phase, from a pressure storagetank Ill which is usually buried in the ground below the frost line toabsorb heat from the surrounding earth. The boiling point of the mixtureis well 10 Claims. (Cl. 62-1) 2 below 32 F., depending upon the amountof pro'- pane contained therein. The vapor pressure in the tank abovethe level of the liquid is sufiicient to discharge liquid from thebottom portion of the tank through an eduction tube II. In thisinstance, the tank is shown as having a riser pipe I2 connected theretowhich carries a combination fitting I3, through which the liquid isadapted to be charged into the tank and dis- 1 pensed therefrom. Oneform of fitting, Awhich forms no part of the present invention, is shownin the aforesaid Patent No. 2,176,829. The liquid i discharged throughthe eduction tube II is delivered from the fitting through a dependingnipple I4 to which is connected an ordinary pressure reducing regulatorI5 by means of an ordinary coupling I6, as shown in the aforesaidpatent.` The riser pipe and the appurtenances connected thereto areshown as being arranged within a housing or casing I1 connected to thetank and extending above the level of the ground so that the fitting I3is easily accessible.

The pressure of the liquid is reduced by the regulator valve to, say,five pounds, gauge. The vapor pressure existing in the tank may varybetween twenty and forty pounds, depending upon the character of thefuel and temperature of the earth around the tank. A part of the liquidflashes into vapor as it passes through the regulator valve because theeducted liquid contains i sufficient sensible heat to vaporize some ofit; while the residual liquid is delivered from the regulator valve inthe form of tiny droplets admixed with the vapor. In this example, themixture of vapor and residual liquid is delivered from the regulatorthrough a pipe I8, shown as bein'g connectedY at its lower end to a Tfitting I9 having a branch vapor conduit 20 connected thereto andleading to a second-stage regulator 2 I, which reduces the pressure ofthe vapo-r to the desired service pressure of about six ounces anddelivers the vapor to an outlet pipe 22 connected to a service line 23.The vapor, which was mixed with the residual liquid, passes upwardlythrough the vapor conduit 2li; while the residual liquid is separatedtherefrom in the T fitting I9 and is regulators, is vaporized byabsorbing heat not only from the contents of the tank but also from anexternal heating medium, to insure complete vaporization and to enablethe system tocarry a heavy load. The pipe 24 is shown as being bentaround the end head 2B of the tank and extending downwardly to a pointwhere it is connected to a vaporizing chamber, shown as being in theform oi a half cylinder 2B arranged within a cylindrical casing 21extending horizontally through the head 2li into the bottom portion ofthe tank I0, so that it'can absorb heat from the liquid fuel in thetank. The casing 21 may be, and preferably is,v in the form of a largepipe closed at its inner end, so that the liquid in the tank cannot comeinto' direct contact `with the wallsof the vaporizer 26. As clearlyshown in Fig. 1, the pipe or easing 21 is preferably welded to the head25. The vaporizer chamber 2B is shown as 'having an upstanding nipple 2lto which the pipe 24 is removably connected, the arrangement being suchthat the vaporizer can be removed through the open end of the casing.The casing 21 is shown as having a `slot 29 through which the nippleprojects to permit removal of the vaporizer chamber.

-The vaporizer chamber is arranged to absorb heat delivered from thefuel contents of the tank through the casing 21. To supplement thesupply of heat for vaporizing the residual liquid, and to increase thevaporizing capacity of the system,

' v there is shown a separate liquid heat exchanger through which aliquid heating medium is circulated to deliver its heat to the vaporizercompartment 28., In this example, a. semi-cylindrical compartment 30 isinserted in the bottom portion of the casing 21 and is connected to aninlet nipple 3l of a water service pipe. A longitudinal baille 32. shownas extending to a point near the inner end of the compartment, isspot-welded in the central portion thereof to insure circulation of thewater inwardly through the left hand side, as shown in Fig. 2, andoutwardly through the right handv side to an outlet nipple I3 leading tothe house. These nipples are, likewise, arranged in slots provided inthe casing 21, so that the compartment 30 can be removed. Thearrangement of the liquid heat exchanger in the bottom of the casingfacilitatesheat transfer upwardly to the vaporizing compartment 26, dueto the natural tendency of the heat to rise therein. It will beunderstood that some of the contained heat in the circulating liquidwill also be delivered to the contents of the tank and thereby increasethe temperature of the fuel and thus increase the vaporizing capacity ofthe system. 'I'he arrangement of the separate liquid heating mediumcompartment in the casing, out of direct contact with the high pressureliquid fuel, insures safety,

in operation because it eliminatesy the danger of fuel entering aruptured compartment or pipe and mixing with the liquid heating medium,which might cause an explosion when ignited.

It will be understood that the residual liquid -between the tworegulators flows downwardly through the pipe 24 along its bottom walland the vapor returns from the vaporizer through the same pipe. It isthen delivered with the separated, flashed vapor, through the pipe andthe second-stage or vapor regulator to the service pipe 22. Y

In this example, a re-vaporizer is also associated with the vaporizer28. The service line 22 is shown as extending upwardly from a pointadjacent to one end of the tank to provide a low point in the line towhich liquid condensate will drain. At this point, there is shown a, Tfitting 24 in the service line, to which a depending pipe 25 isconnectedleading to a re-vaporizer,

shown as being in the form of a spur tube 22, extending into thevaporizing compartment 26 and having an upstanding nipple 31 adjacent tothe nipple 28. The re-vaporlzer requires much less heat than thevaporizer, because only a small quantity of condensate. 'formed when thesystem is overloaded or during extremely cold weather, is required to bere-vaporized and it is at a much lower pressure than the pressureexisting in the vaporizer. It absorbs its heat from the residual liquidand vapor in the vaporizer. The condensate will be re-vaporized quicklyand the vapor returned to the service line through the depending pipe 25without conflicting with the draining condensate.

The vaporizer and re-vaporizer, together with the liquid heat exchanger,can be, and preferably are, assembled in a system before it is trans?ported to the place of installation. In fact, the whole system ispreferably assembled as a. com plete unit and the pipes, which arearranged ador cap 38, telescoped over the outer end of the casing, whichextends beyond the upstanding pipe nipples or connections. This preventsdirt or mud from entering the casing around the compartments and thusfacilitates removal o! the compartments for repairs or replacements.

From the foregoing description, it will be understood that thecombination vaporizer and revaporizer. arranged to absorb heat from thefuel contents of the tank, as well as from an external source, greatlyincrease the capacity and eiliciency of a two-stage liquid eductlonsystem. The parts are all easily accessible from the outside of thetank, where they can be removed for inspection and repairs. Thesemi-cylindrical compartments may be made by splitting a piece ofstandard pipe and welding flat walls on the split parts.

Having thus described the invention, what is claimed is:

1. In combination with a liquefied petroleum gas generating anddispensing system of the type wherein liquid fuel is delivered from thebottom of the tank through a first-stage pressure reducing regulator andpartially vaporized, a heat exchanging casing projecting into the bottomportion of the tank and submerged in the liquid fuel; a vaporizer forthe residual liquid delivered from the first-stage pressure reducingregulator removably mounted in said casing; conduit means connected todeliver the residual liquid to said vaporizer and return the vaportherefrom; and

a second-stage pressure reducing regulator com municating with lsaidconduit means and through which the vapor from the first-stage regulatorand the vapor generated in said vaporizer are delivered: and a servicepipe connected to the second-stage regulator.

2. In combination with a liquefied petroleum gas generating anddispensing system of the type wherein liquid fuel is delivered from thebottom of the tank through a first-stage pressure reducing regulator andpartially vaporized a heat exchanging casing projecting into the bottomportion of the tank and submerged in the liquid fuel; a vaporizer forthe residual liquid delivered from the first-stage regulator removablymounted in said casing; a pipe connecting the first-stage regulator todeliver the residual liquid to said vaporizer and return the vaportherefrom; a supplemental vheat exchanger also arranged in l said casingutilizing a circulating liquid as a heating medium for transferringvaporizing heat to the' residual liquid; a second-stage pressurereducing regulator connected to said pipe and through which the vapor isdelivered at service pressure; and a.` service pipe connected to thesecond-stage regulator.

3. In combination with a liqueiied petroleum gas generating anddispensing system of the type wherein liquid vfuel is delivered from thebottom o! the tank through a ilrst-stage pressure reducing regulator andpartially vaporized. a heat exchanging casing projecting into the bottoma service pipe connected to the second-stage regulatorand having a lowpoint adjacent to the tank; a depending condensate drain pipe con-Vnected to the service pipe; and a re-vaporizer for the condensate alsoarranged within said casing adjacent to the vaporlzer and connected tosaid drain pipe.

4. In a liquefied petroleum gas generating and dispensing system of theliquid eduction type wherein the liquid is delivered from a pressurestorage tank through a first-stage pressure reducing regulator and thegenerated gas passes through a second-stage pressure reducing regulatorto a service pipe', heat exchanging means between the regulatorscomprising a casing extending into the tank below the liquid level andhaving an open end outside the tank; an elongated vaporizer removablymounted in said casing connected to receive residual liquid deliveredIfrom the first-stage regulator and to deliver generated gas through thesecond-stage regulator; and an additional heat exchangeremployingacirculating liquid as the heating medium also removablymounted in said casing to deliver supplemental heat to the vaporizer.

5. In ay liquefied petroleum gas generating and dispensing system of theliquid eduction type wherein the liquid is delivered from'a pressurestorage tank through a rst-stage pressure reducing regulator and thegenerated gas passes through a second-stage pressure reducing regulatorto a service pipe, heat exchanging means between the regulatorscomprising a casing extending into the tank below the liquid level andhaving an open end outside the tank; an elongated vaporizer' removablymounted in said casing connected to receive residual liquid deliveredfrom the first-stage regulator and to deliver generated gas through thesecond-stage regulator; a re-vaporizer connected to receive condensatefrom a low point in the gas service pipe also removably mounted in saidcasing and associated with the vaporizer; and an additional heatexchanger in the casing employing circulating water. as a heating mediumto supply supplemental heat to the vaporizer and re-vaporizer.

6. In a liquefied petroleum gas generating and dispensing system of theliquid eduction type wherein the liquid is delivered from a pressurestorage tank through a first-stage pressure re- 6 ducing regulator andthe generated gas passes through a second-stage pressure reducingregulator. to a. service pipe, heat exchanging means between theregulators comprising a casing in the form of a large -pipe extendinginto the tank below the liquid level and having an open end extendingoutside the tank, a vaporizer in the form of a portion of a cylinderinserted in said pipe and connected to receive residual liquid deliveredfrom the first stage regulator and to deliver generated gas through thesecond-stage regulator; a re-vaporizer,` in the form of a spurtube inthe vaporizer, connected to receive condensate drained from a low pointin the gas service line and to return vapor thereto; a supplemental heatexchanger, likewise in theform of a portion of a cylinder, inserted inthe bottom portion of said pipe in heat exchanging contact with thevaporizer compartment; water inlet and outlet pipes connected to theouter end of the supplemental heat exchanger; and a longitudinalbaille'between the water inlet and outlet connections to cause thewatertocirculate back and forth throughout the length of thesupplemental heat exchanger.

7. In a liqueiled petroleum gas generating and dispensing system, as setforth in claim I6, wherein the compartments constituting the vaporizer,and the water heat-exchanging compartments are semi-cylindrical,complemental and substantially nll the large pipe, being removablymounted therein; and wherein a closure cap is mounted on the outsideopen end of saidvlarge pipe.

8. .In a liquefied petroleum gas generating and dispensing systemwherein fluid is delivered from a pressure storage tank through ailrst-stage pressure reducing regulator and fluid of reduced pressurethen passes through a second-stage pressure reducing regulator to aservice pipe, heat exchanging means between the regulators comprlsing anelongated casing extending :into the tank below the liquid level andhaving an open end outside the tank; a first means in said casingconnected to receive residual liquid delivered from the ilrst stageregulator and to deliver generated gas through the second-stageregulator; and a second means connected to receive condensate from a lowpoint in the gas service' pipe also mounted in said casing andassociated with said rst mentioned means to deliver revaporized gastothe service pipe.

9. Apparatus, as set forth in claim 8, wherein said ilrst and secondmeans comprise a vaporizer and a re-vaporizer both removably mounted insaid elongated casing.

10. In a liqueed petroleum gas generating and I dispensing systemwherein iluid is delivered from a pressure storage tank through atiret-stage pressure reducing regulator and iluid of reduced pressurethen passes through a second-stage pressure reducing regulator to aservice pipe, heat exchanging means between the regulators comprising anelongated casing extending into the tank below the liquid level andhaving an `open rend outside the tank; a ilrst means in said casingconnected to receive residual liquid delivered from the first-stageregulator and to deliver generated gas through the second-stageregulator; a second means connected to receive condensate from a lowpoint' in the gas service pipe also mounted in said casing andassociated with'said rst mentioned means; and an additional heatexchanger in the casing employing a circulating medium as a source ofheat to supply supplemental heat to said nrs-t and second mentioned meer this patent: A '2.286.050

means. 1

LOYD J. Number REFERENCES CITED 5 2,217,583

The following references are of record in the 2360.356

